In producing a "breathable" textile material, it is known in the art to laminate a substrate fabric to a second layer of material by means of an adhesive layer. In order to impart certain permeability characteristics to the resulting laminates, e.g., air permeability or moisture permeability, it is also known in the art to apply the adhesive discontinuously, i.e., leave certain areas of the laminates unbonded. A variety of bonding methods have been utilized in the past to achieve the aforementioned discontinuous adhesive layer, but these methods suffer from significant disadvantages.
One method disclosed in U.S. Pat. Nos. 5,342,469 and 5,705,011 involves introduction of a discontinuous adhesive in the form of linear filaments between the fabric layers to be laminated. An obvious drawback of this method is that there is no way to control the number and locations of the voids in the adhesive layer. Another method disclosed in U.S. Pat. No. 5,560,974 involves applying an adhesive layer at discrete, spaced-apart locations, which adhesive layer may form a series of spots or a lined pattern. Other techniques which have been utilized in attempts to create a discontinuous adhesive layer between laminate layers include controlled extrusion through a die applicator, rotogravure, dot gravure, flexographic, screen printing, melt-blowing and ink-jet printing. An exemplary technique, disclosed in U.S. Pat. No. 4,761,324, involves the use of a printing roll that has a void pattern. In this known technique, the printing roll transfers the adhesive to the fabric only where the roll contacts the fabric. In screen printing, selected sections of the screen are blocked off and adhesive is applied through the remaining portions of the screen.
The above-mentioned prior art techniques have some significant cost and technical disadvantages. Regarding the printing-roll adhesive application method and the screen-print adhesive application method, engraving new or modified patterns into metal/ceramic rolls or screens is costly. Furthermore, roll changes required between successive adhesive-application jobs are very time consuming, requiring adhesive cleanups. In addition, fine, adhesive void patterns are difficult to achieve, especially when a thick adhesive layer is desired. Regarding the process for controlled extrusion of adhesive through a die applicator, the initial capital investment for the necessary equipment is relatively high. Furthermore, fine adhesive void patterns are difficult to achieve with this method.
Accordingly, it would be desirable to have a method for applying a discontinuous layer of adhesive for textile lamination, which method eliminates the disadvantages associated with previously known techniques.